Communication management system and communication management method

ABSTRACT

In a communication management system, a communication control apparatus includes: a normal signature list which stores a list of signatures of normal communication; a search circuit which acquires communication data and searches the normal signature list storing signatures of normal communication to check if the signature of the communication data appears in the list; and a process execution circuit functioning as a warning unit which issues a warning when there is detected communication data of which the signature does not match any signature of normal communication stored in the normal signature list. An operator terminal includes: a determination result acquisition unit which acquires a determination result indicating whether or not communication data against which a warning has been issued is normal; and a normal signature list update unit which, when the determination result acquisition unit acquires a determination result that communication data against which a warning has been issued is found to be normal, adds the signature of the communication data to a normal signature list.

TECHNICAL FIELD

The present invention relates to a communication management technique,and particularly to a communication management system and acommunication management method for managing inappropriatecommunication.

BACKGROUND ART

Due to improved Internet infrastructures and the widespread ofcommunication terminals, such as cellular phone terminals, personalcomputers, and VoIP (Voice over Internet Protocol) phone sets, thenumber of Internet users is now exploding. Under such circumstances,security problems such as computer viruses, hacking and spam mails havebecome apparent, requiring appropriate techniques for communicationcontrol. Also, since improved communication environments have enormouslyincreased communication traffic, there are required communicationcontrol apparatuses that enable high-speed processing of a large volumeof data.

[Patent Document 1] Japanese Patent Application Laid-open No. 4-180425.

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

In recent years, there have been found malicious programs (malware) thatare primarily intended to infect computers to damage them or to use suchcomputers as zombie computers for sending spam mails or performing DDoSattacks, and such programs are regarded as a serious issue. Thesemalicious programs are called “bots”, and since a bot operates accordingto external instructions, an infected computer can be manipulated fromthe outside through a bot. Moreover, if a number of computers areinfected by the same bot, such computers can be operated simultaneouslyunder a single instruction, which may cause severe damage.

It is difficult to rely on antivirus software or the like to detect abot, because new bot variants are created constantly. In addition,attackers are able to use their own protocols to give instructions foroperating bots, thereby making the detection of bots more difficult.

The present invention has been made in view of such a situation, and ageneral purpose thereof is to provide a technique for managinginappropriate communication.

Means for Solving the Problem

One aspect of the present invention relates to a communicationmanagement system. The communication management system comprises: anormal signature list which stores a list of signatures of normalcommunication; a first search unit which acquires communication data andsearches the normal signature list storing signatures of normalcommunication to check if the signature of the communication dataappears in the list; and a warning unit which issues a warning whenthere is detected communication data of which the signature does notmatch any signature of normal communication stored in the normalsignature list.

The communication management system may further comprise: adetermination result acquisition unit which acquires a determinationresult indicating whether or not communication data against which awarning has been issued is normal; and a normal signature list updateunit which, when the determination result acquisition unit acquires adetermination result that communication data against which a warning hasbeen issued is found to be normal, adds the signature of thecommunication data to the normal signature list.

The communication management system may further comprise: an abnormalsignature list which stores a list of signatures of communication to beblocked; a second search unit which acquires communication data andsearches the abnormal signature list storing signatures of communicationto be blocked to check if the signature of the communication dataappears in the list; and a blocking unit which, when there is detectedcommunication data of which the signature matches a signature ofcommunication to be blocked stored in the abnormal signature list,blocks the communication data.

The determination result acquisition unit may further acquire adetermination result indicating whether or not communication dataagainst which a warning has been issued should be blocked. Thecommunication management system may further comprise an abnormalsignature list update unit which, when the determination resultacquisition unit acquires a determination result that communication dataagainst which a warning has been issued should be blocked, adds thesignature of the communication data to the abnormal signature list.

The communication management system may further comprise: a ruledatabase which stores a rule for extracting communication data requiredto be analyzed among acquired communication data; a third search unitwhich acquires communication data and searches the rule database tocheck if the communication data complies with a rule stored in thedatabase; and an extraction unit which, when there is detectedcommunication data complying with a rule stored in the rule database,extracts the communication data.

The communication management system may further comprise a rule databaseupdate unit which adds, to the rule database, a rule for extractingcommunication data associated with communication data against which awarning has been issued.

At least two of the first search unit, the second search unit and thethird search unit may be configured with FPGAs (Field Programmable GateArray) or wired logic circuits. Also, at least two of the first searchunit, the second search unit and the third search unit may performsearches simultaneously in parallel.

Another aspect of the present invention relates to a communicationmanagement method. The communication management method comprises:searching, upon acquisition of communication data, a normal signaturelist storing a list of signatures of normal communication so as to checkif the signature of the communication data appears in the list; andissuing a warning when there is detected communication data of which thesignature does not match any signature of normal communication stored inthe normal signature list.

Optional combinations of the aforementioned constituting elements, andimplementations of the invention in the form of methods, apparatuses,systems, recording mediums and computer programs may also be practicedas additional modes of the present invention.

ADVANTAGEOUS EFFECTS

The present invention provides a technique for managing inappropriatecommunication.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram that shows a configuration of a communicationcontrol system according to a base technology.

FIG. 2 is a diagram that shows a configuration of a conventionalcommunication control apparatus.

FIG. 3 is a diagram that shows a configuration of a communicationcontrol apparatus according to the base technology.

FIG. 4 is a diagram that shows a configuration of a packet processingcircuit.

FIG. 5 is a diagram that shows a configuration of a position detectioncircuit.

FIG. 6 is a diagram that shows another example of the position detectioncircuit.

FIG. 7 is a diagram that shows yet another example of the positiondetection circuit.

FIG. 8 is a diagram that shows an example of internal data of a firstdatabase.

FIG. 9 is a diagram that shows another example of internal data of thefirst database.

FIG. 10 is a diagram that shows yet another example of internal data ofthe first database.

FIG. 11 is a diagram that shows another example of the index circuit.

FIG. 12 is a diagram that shows a configuration of a comparison circuitincluded in a binary search circuit.

FIG. 13 is a diagram that shows a configuration of the binary searchcircuit.

FIG. 14 is a diagram that shows still yet another example of internaldata of the first database.

FIG. 15 is a diagram that shows an example of internal data of a seconddatabase.

FIG. 16 is a diagram that shows another example of internal data of thesecond database.

FIG. 17 is a diagram that shows another illustrative configuration ofthe communication control apparatus according to the base technology.

FIG. 18 is a diagram that shows a configuration of a communicationcontrol apparatus comprising multiple communication control apparatuses.

FIG. 19 is a diagram that shows an example of internal data of amanagement table provided in an operation monitoring server.

FIG. 20 is a diagram for describing an operational procedure performedin the event that a communication control apparatus fails.

FIGS. 21A, 21B and 21C are diagrams for describing a procedure forupdating databases in the communication control apparatuses.

FIG. 22 is a diagram that shows a configuration of a communication pathcontrol apparatus provided to process packets with multiplecommunication control apparatuses.

FIG. 23 is a diagram that shows a configuration of a communicationmanagement system according to an embodiment.

EXPLANATION OF REFERENCE NUMERALS

-   -   10 communication control apparatus    -   20 packet processing circuit    -   30 search circuit    -   32 position detection circuit    -   33 comparison circuit    -   34 index circuit    -   35 comparison circuit    -   36 binary search circuit    -   36A, 36B and 36C comparison circuits    -   36Z control circuit    -   40 process execution circuit    -   50 first database    -   60 second database    -   100 communication control system    -   110 operation monitoring server    -   120 connection management server    -   130 message output server    -   140 log management server    -   150 database server    -   200 communication path control apparatus    -   300 communication management system    -   310 user terminal    -   320 bot    -   322 botnet    -   332 normal signature list    -   334 abnormal signature list    -   336 rule database    -   340 operator terminal    -   342 warning acquisition unit    -   344 communication data acquisition unit    -   346 analysis unit    -   348 determination result acquisition unit    -   352 normal signature list update unit    -   354 abnormal signature list update unit    -   356 rule database update unit    -   362 normal signature list    -   364 abnormal signature list    -   366 rule database    -   390 Internet

BEST MODE FOR CARRYING OUT THE INVENTION

First, as a base technology, a communication control system that has noCPU or OS and performs a packet filtering function using a dedicatedhardware circuit will be described. Thereafter, there will be describedas an embodiment a technique for managing communication in a botnetusing the communication control system of the base technology.

(Base Technology)

FIG. 1 shows a configuration of a communication control system accordingto the base technology. A communication control system 100 comprises acommunication control apparatus 10 and various peripheral apparatusesprovided to support the operation of the communication control apparatus10. The communication control apparatus 10 of the base technologyperforms a packet filtering function provided by an Internet serviceprovider or the like. The communication control apparatus 10 provided ona network path acquires a packet transmitted via the network, analyzesthe content, and determines whether or not the packet communicationshould be permitted. If the communication is permitted, thecommunication control apparatus 10 will transmit the packet to thenetwork. If the communication is prohibited, the communication controlapparatus 10 will discard the packet and return a warning message or thelike to the transmission source of the packet if necessary.

The communication control system 100 of the base technology includesmultiple communication control apparatuses 10 a, 10 b, 10 c, etc. andoperates them functioning as one communication control apparatus 10.Hereinafter, each of the communication control apparatuses 10 a, 10 b,10 c, etc. and their collective body will be both referred to as acommunication control apparatus 10 with no distinction.

In the communication control system 100 of the base technology, eachcommunication control apparatus 10 stores the respective shares of atleast part of databases necessary for packet processing; there areprovided as many as the number of communication control apparatuses 10required to share and store such databases, and at least one moreapparatus is provided extra. For example, when the number of pieces ofdata is 300,000 or above but less than 400,000, the number ofcommunication control apparatuses required for operation is four.However, one or more communication control apparatuses 10 should befurther provided as standby units in case any of the communicationcontrol apparatuses 10 in operation fails or in case a database in anyof the communication control apparatuses 10 is updated. Accordingly, atleast five communication control apparatuses 10 are provided in total.Conventionally, the entire system has needed to be duplexed consideringfault tolerance. According to the technique of the base technology, incontrast, a divided unit of the communication control apparatus 10 maybe only provided extra, thereby enabling cost reduction. The operatingstate of the multiple communication control apparatuses 10 a, 10 b, 10c, etc. is managed by an operation monitoring server 110. The operationmonitoring server 110 of the base technology has a management table formanaging the operating state of the communication control apparatuses.

The peripheral apparatuses include the operation monitoring server 110,a connection management server 120, a message output server 130, a logmanagement server 140 and a database server 150. The connectionmanagement server 120 manages connection to the communication controlapparatus 10. When the communication control apparatus 10 processes apacket transmitted from a cellular phone terminal, for example, theconnection management server 120 authenticates the user as a userentitled to enjoy the service of the communication control system 100,based on information included in the packet, which uniquely identifiesthe cellular phone terminal. Once the user is authenticated, packetstransmitted from the IP address, which is temporarily provided for thecellular phone terminal, will be transmitted to the communicationcontrol apparatus 10 and processed therein, without being authenticatedby the connection management server 120 during a certain period. Themessage output server 130 outputs a message to the destination or thesource of packet transmission, according to whether the communicationcontrol apparatus 10 has permitted the packet communication. The logmanagement server 140 manages the operating history of the communicationcontrol apparatus 10. The database server 150 acquires the latestdatabase from an external source and provides the database to thecommunication control apparatus 10. To update the database withouthalting the operation of the communication control apparatus 10, theapparatus may possess a backup database. The operation monitoring server110 monitors the operating state of the communication control apparatus10 and its peripheral apparatuses including the connection managementserver 120, message output server 130, log management server 140 anddatabase server 150. The operation monitoring server 110 has the highestpriority in the communication control system 100 and performssupervisory control of the communication control apparatus 10 and allthe peripheral apparatuses. Although the communication control apparatus10 is configured with a dedicated hardware circuit, as will be describedlater, the operation monitoring server 110 can monitor the operatingstate even while the communication control apparatus 10 is in operation,by inputting to or outputting from the communication control apparatus10 the data for monitoring by means of a boundary-scan circuit based onthe technique described in Japanese Patent No. 3041340 filed by thepresent applicant or other techniques.

In the communication control system 100 of the base technology, as willbe described below, the communication control apparatus 10, configuredwith a dedicated hardware circuit for faster operation, is controlled byusing a group of peripheral servers connected thereto and having variousfunctions. Accordingly, by suitably replacing the software of the groupof servers, a wide variety of functions can be achieved with a similarconfiguration. Thus, the base technology provides such communicationcontrol system having high flexibility.

FIG. 2 shows a configuration of a conventional communication controlapparatus 1. The conventional communication control apparatus 1comprises a communication control unit 2 on the receiving side, a packetprocessing unit 3, and a communication control unit 4 on the sendingside. The communication control units 2 and 4 include PHY processingunits 5 a and 5 b for performing physical layer processing of packets,and MAC processing units 6 a and 6 b for performing MAC layer processingof packets, respectively. The packet processing unit 3 includes protocolprocessing units for performing protocol-specific processing, such as anIP processing unit 7 for performing IP (Internet Protocol) processingand a TCP processing unit 8 for performing TCP (Transport ControlProtocol) processing. The packet processing unit 3 also includes an APprocessing unit 9 for performing application layer processing. The APprocessing unit 9 performs filtering or other processing according todata included in a packet.

The packet processing unit 3 of the conventional communication controlapparatus 1 is implemented by software, using a general-purposeprocessor, or CPU, and an OS running on the CPU. With suchconfiguration, however, the performance of the communication controlapparatus 1 depends on the performance of the CPU, hampering thecreation of a communication control apparatus capable of high-speedprocessing of a large volume of packets. For example, a 64-bit CPU canprocess only up to 64 bits at a time, and hence, there has existed nocommunication control apparatus having a higher performance than this.In addition, since the conventional communication control apparatus ispredicated on the presence of an OS with versatile functionality, thepossibility of security holes cannot be eliminated completely, requiringmaintenance work including OS upgrades.

FIG. 3 shows a configuration of a communication control apparatusaccording to the base technology. A communication control apparatus 10of the base technology comprises a packet processing circuit 20configured with dedicated hardware employing a wired logic circuit,instead of a packet processing unit that is implemented by softwareincluding a CPU and an OS in a conventional communication controlapparatus. By providing a dedicated hardware circuit to processcommunication data, rather than processing it with an OS and softwarerunning on a general-purpose processing circuit such as CPU, theperformance limitations posed by the CPU or OS can be overcome, enablinga communication control apparatus having high throughput.

For example, a case will be considered here in which search is conductedin packet filtering or the like to check if the data in a packetincludes reference data, which serves as criteria for filtering. When aCPU is used to compare the communication data with the reference data,there occurs a problem in that, since only 64-bit data can be comparedat a time, the processing speed cannot be improved beyond such CPUperformance. Since the CPU needs to repeat the process of loading 64bits of communication data into a memory and comparing it with thereference data, the memory load time becomes a bottleneck that limitsthe processing speed.

In the base technology, by contrast, a dedicated hardware circuitconfigured with a wired logic circuit is provided to comparecommunication data with reference data. This circuit includes multiplecomparators arranged in parallel, so as to enable the comparison of datahaving a length greater than 64 bits, such as 1024 bits. By providingdedicated hardware in such manner, bit matching can be simultaneouslyperformed on a large number of bits in parallel. Since 1024-bit data canbe processed at a time, while the conventional communication controlapparatus 1 using a CPU processes only 64 bits, the processing speed canbe improved remarkably. Increasing the number of comparators willimprove the throughput, but also increase the cost and size of theapparatus. Accordingly, an optimal hardware circuit may be designed inaccordance with the desired performance, cost or size.

Since the communication control apparatus 10 of the base technology isconfigured with dedicated hardware employing a wired logic circuit, itdoes not require any OS (Operating System). This can eliminate the needfor the installation, bug fixes, or version upgrades of an OS, therebyreducing the cost and man-hours required for administration andmaintenance. Also, unlike CPUs requiring versatile functionality, thecommunication control apparatus 10 does not include any unnecessaryfunctions or use needless resources, and hence, reduced cost, a smallercircuit area or improved processing speed can be expected. Furthermore,again unlike conventional OS-based communication control apparatuses,the absence of unnecessary functions decreases the possibility ofsecurity holes and thus enhances the tolerance against attacks frommalicious third parties over a network.

The conventional communication control apparatus 1 processes packetsusing software predicated on a CPU and an OS. Therefore, all packet dataneeds to be received before protocol processing is performed, and thenthe data is passed to an application. In contrast, since packetprocessing is performed by a dedicated hardware circuit in thecommunication control apparatus 10 of the base technology, all packetdata need not be received before starting the processing; upon receptionof necessary data, the processing can be started at any given point intime without waiting for the reception of subsequent data. For example,position detection processing in a position detection circuit, whichwill be described later, may be started at the time when positionidentification data for identifying the position of comparison targetdata is received. Thus, various types of processing can be performed inparallel without waiting for the reception of all data, reducing thetime required to process packet data.

FIG. 4 shows an internal configuration of the packet processing circuit.The packet processing circuit 20 comprises: first databases 50A, 50B and50C (hereinafter, they may be collectively referred to as “firstdatabases 50”) for storing reference data, which is referred to whenprocessing to be performed on communication data is determined; a searchcircuit 30 for searching received communication data for the referencedata by comparing the two; a second database 60 for storing a searchresult of the search circuit 30 and a content of processing to beperformed on the communication data, which are related to each other;and a process execution circuit 40 for processing the communication databased on the search result of the search circuit 30 and the conditionsstored in the second database 60.

The search circuit 30 includes: a position detection circuit 32 fordetecting the position of comparison target data, which is to becompared with reference data, in communication data; an index circuit 34which serves as an example of a determination circuit that determineswhich range the comparison target data belongs to among three or moreranges, into which the reference data stored in the first database 50 isdivided; and a binary search circuit 36 for searching the determinedrange for the reference data that matches the comparison target data.The reference data may be searched for the comparison target data usingany search technique, and a binary search method is used in the basetechnology. Since an improved binary search method is employed, as willbe discussed later, three first databases 50 are provided in the basetechnology. The first databases 50A, 50B and 50C store the samereference data.

FIG. 5 shows an internal configuration of the position detectioncircuit. The position detection circuit 32 includes multiple comparisoncircuits 33 a-33 f that compare communication data with positionidentification data for identifying the position of comparison targetdata. While six comparison circuits 33 a-33 f are provided here, thenumber of comparison circuits may be arbitrary, as will be describedlater. To the comparison circuits 33 a-33 f are input pieces ofcommunication data, with each piece shifted from the preceding one by apredetermined data length, such as 1 byte. These multiple comparisoncircuits 33 a-33 f then simultaneously compare the respectivecommunication data with the position identification data to be detectedin parallel.

The base technology will be described by way of example for explainingthe operation of the communication control apparatus 10, in which acharacter string “No. ###” in communication data is detected, the number“###” included in the character string is then compared with referencedata, and if the number matches the reference data, the packet will beallowed to pass, while, if they do not match, the packet will bediscarded.

In the example of FIG. 5, communication data “01No. 361 . . . ” is inputto the comparison circuits 33 a-33 f with a shift of one character each,and position identification data “No.” for identifying the position ofthe number “###” is sought to be detected in the communication data.More specifically, “01N” is input to the comparison circuit 33 a, “1No”to the comparison circuit 33 b, “No.” to the comparison circuit 33 c,“o.” to the comparison circuit 33 d, “. 3” to the comparison circuit 33e, and “36” to the comparison circuit 33 f. Then, the comparisoncircuits 33 a-33 f simultaneously perform comparisons with the positionidentification data “No.”. Consequently, there is found a match with thecomparison circuit 33 c, indicating that the character string “No.”exists at the third character from the top of the communication data.Thus, it is found that the numeral data as comparison target data existssubsequent to the position identification data “No.” detected by theposition detection circuit 32.

When the same processing is performed by a CPU, since the comparisonprocess needs to be serially performed one by one from the top, such ascomparing character strings “01N” and “No.” before comparing “1No” and“No.”, no improvement of detection speed can be expected. In thecommunication control apparatus 10 of the base technology, in contrast,providing the multiple comparison circuits 33 a-33 f in parallel enablessimultaneous parallel comparison processing, which could not have beenperformed with a CPU, improving the processing speed significantly.Providing more comparison circuits will improve the detection speed, asmore characters can be compared simultaneously. In consideration of costor size, a sufficient number of comparison circuits may be provided toachieve a desired detection speed.

Aside from detecting position identification data, the positiondetection circuit 32 may also be used as a circuit for detectingcharacter strings for various purposes. Moreover, the position detectioncircuit 32 may be configured to detect position identification data inunits of bits, not just as a character string.

FIG. 6 shows another example of the position detection circuit. In theexample shown in FIG. 6, when the data length of position identificationdata is shorter than that prepared in each of the comparison circuits 33a-33 f in the position detection circuit 32, predetermined data, such as“00H” or “01H”, is padded posterior to the position identification data.Similarly, with regard to communication data to be compared withposition identification data, a data length identical with that of theposition identification data is extracted from the communication dataand input to a comparison circuit, and the same data as padded after theposition identification data is also padded posterior thereto. In suchcase, the communication data may be copied as work, and the copied datamay be processed to be input to the comparison circuits 33 a-33 f, so asnot to change the original communication data. Thus, the positiondetection circuit 32 can be generally used regardless of the length ofposition identification data.

FIG. 7 shows yet another example of the position detection circuit. Inthe example shown in FIG. 7, predetermined data is padded posterior toposition identification data in the same way as shown in the example ofFIG. 6, and, in addition, such data is regarded as a wild card. That is,when data is input as a wild card into the comparison circuits 33 a-33f, it is determined that the corresponding part of target data to becompared matches the wild-card data whatever the target data is. Thus,the position detection circuit 32 can be generally used regardless ofthe length of position identification data.

FIG. 8 shows an example of internal data of the first database. Thefirst database 50 stores reference data, which is referred to whenprocessing on packets, such as filtering, routing, switching, orreplacement, is determined. The pieces of reference data are sortedaccording to some sort conditions and stored in ascending or descendingorder. In the example of FIG. 8, 1000 pieces of reference data arestored.

The index circuit 34 determines which range comparison target databelongs to among three or more ranges, such as 52 a-52 d, into whichreference data stored in the first database 50 is divided. In theexample of FIG. 8, the 1000 pieces of reference data are divided intofour ranges 52 a-52 d, i.e., 250 pieces each in a range. The indexcircuit 34 includes multiple comparison circuits 35 a-35 c, each ofwhich compares a piece of reference data at the border of the range withthe comparison target data. Since the comparison circuits 35 a-35 csimultaneously compare the pieces of reference data at the borders withthe comparison target data in parallel, which range the comparisontarget data belongs to can be determined by a single operation ofcomparison processing.

The pieces of reference data at the borders to be input to thecomparison circuits 35 a-35 c of the index circuit 34 may be set by anapparatus provided outside the communication control apparatus 10.Alternatively, reference data at predetermined positions in the firstdatabase 50 may be set in advance to be automatically input as such. Inthe latter case, even when the first database 50 is updated, thereference data at the predetermined positions in the first database 50are automatically input to the comparison circuits 35 a-35 c. Therefore,the communication control processing can be performed immediatelywithout initialization or the like.

As mentioned previously, CPU-based binary search cannot make multiplecomparisons at the same time. In the communication control apparatus 10of the base technology, in contrast, providing the multiple comparisoncircuits 35 a-35 c in parallel enables simultaneous parallel comparisonprocessing, with a significant improvement in the search speed.

After the index circuit 34 determines the relevant range, the binarysearch circuit 36 performs search using a binary search method. Thebinary search circuit 36 divides the range determined by the indexcircuit 34 further into 2^(n) and subsequently compares the pieces ofreference data lying at the borders with the comparison target data,thereby determining which range the comparison target data belongs to.The binary search circuit 36 includes multiple comparators forcomparing, bit by bit, reference data with comparison target data. Forexample, in the base technology are provided 1024 comparators to performbit matching on 1024 bits simultaneously. When the range to which thecomparison target data belongs is determined among the 2^(n) splitranges, the determined range is further divided into 2^(n). Then, thepieces of reference data lying at the borders are read out to becompared with the comparison target data. Thereafter, this processing isrepeated to narrow the range further until reference data that matchesthe comparison target data is eventually found.

The operation will now be described in more detail in conjunction withthe foregoing example. Each of the comparison circuits 35 a-35 c of theindex circuit 34 receives “361” as comparison target data. As forreference data, the comparison circuit 35 a receives “378”, which liesat the border of the ranges 52 a and 52 b. Similarly, the comparisoncircuit 35 b receives reference data “704” lying at the border of theranges 52 b and 52 c, and the comparison circuit 35 c receives referencedata “937” lying at the border of the ranges 52 c and 52 d. Thecomparison circuits 35 a-35 c then perform comparisons simultaneously,determining that the comparison target data “361” belongs to the range52 a. Subsequently, the binary search circuit 36 searches the referencedata for the comparison target data “361”.

FIG. 9 shows another example of internal data of the first database. Inthe example shown in FIG. 9, the number of pieces of reference data issmaller than the number of pieces of data storable in the first database50, i.e., 1000 in this case. In such instance, the first database 50stores the pieces of reference data in descending order, starting withthe last data position therein. Then, 0 is stored in the rest of thedata positions. The database is loaded with data not from the top butfrom the bottom of the loading area, and all the vacancies occurring inthe front of the loading area, if any, are replaced with zero.Consequently, the database is fully loaded at any time, so that thesearch time necessary for binary search will be constant. Moreover, ifthe binary search circuit 36 reads reference data “0” during a search,the circuit can identify the range without making a comparison, as thecomparison result is obvious, and can proceed to the next comparison.Consequently, the search speed can be improved.

In CPU-based software processing, the first database 50 stores pieces ofreference data in ascending order, from the first data position therein.In the rest of data positions will be stored a maximum value or thelike, and in such case, the skip of comparison processing as describedabove cannot be made during binary search. The comparison techniquedescribed above can be implemented by configuring the search circuit 30with a dedicated hardware circuit.

FIG. 10 shows yet another example of internal data of the firstdatabase. In the example shown in FIG. 10, the reference data is notevenly divided into three or more ranges, but unevenly divided intoranges that accommodate different numbers of pieces of data, such as 500pieces in the range 52 a and 100 pieces in the range 52 b. These rangesmay be determined depending on the distribution of frequencies withwhich reference data occurs in communication data. Specifically, theranges may be determined so that the sums of the frequencies ofoccurrence of reference data belonging to the respective ranges arealmost the same. Accordingly, the search efficiency can be improved. Thereference data to be input to the comparison circuits 35 a-35 c of theindex circuit 34 may be modifiable from the outside. In such case, theranges can be dynamically set, so that the search efficiency will beoptimized.

FIG. 11 shows another example of the index circuit. In the examples ofFIGS. 8-10, the index circuit 34 uses the three comparison circuits 35a-35 c to determine which range comparison target data belongs to amongthe four ranges of 52 a-52 d in the first database 50. In the exampleshown in FIG. 11, on the other hand, the index circuit 34 is providedwith four comparison circuits 35 d-35 g for determining whether or notcomparison target data is included in each of the four ranges 52 a-52 d.For example, into the comparison circuit 35 d are input the 0th and250th pieces of reference data in the first database 50 and comparisontarget data. Then, each piece of the reference data is compared to thecomparison target data, so as to determine whether or not the referencedata is included in the range 52 a. The comparison results provided bythe comparison circuits 35 d-35 g are input into a determination circuit35 z, which outputs information providing which range the reference datais included in. Each of the comparison circuits 35 d-35 g may output aresult indicating whether the reference data is included between the twoinput pieces of reference data, or may output a result indicating thatthe reference data is greater than the range, the reference data isincluded in the range, or the reference data is smaller than the range.When it is determined that the comparison target data is not included inany of the ranges 52 a-52 d, it can be found that the comparison targetdata does not exist within the first database 50. Accordingly, thesearch can be terminated without performing any further binary search.

FIG. 12 shows a configuration of comparison circuits included in thebinary search circuit. As mentioned previously, the comparison circuitin the binary search circuit 36 includes 1024 comparators, such as 36 a,36 b, . . . . Each of the comparators 36 a, 36 b, etc. receives 1 bit ofreference data 54 and 1 bit of comparison target data 56 to compare thebits in value. The comparison circuits 35 a-35 c of the index circuit 34have similar internal configurations. Since the comparison processing isthus performed by a dedicated hardware circuit, a large number ofcomparison circuits can be operated in parallel to compare a largenumber of bits at a time, thereby speeding up the comparison processing.

FIG. 13 shows a configuration of the binary search circuit. The binarysearch circuit 36 includes comparison circuits 36A, 36B and 36C, each ofwhich includes the 1024 comparators 36 a, 36 b, etc. as shown in FIG.12, and a control circuit 36Z for controlling the comparison circuits.

In a conventional binary search method, a piece of data lying at theone-half position in the search range of a database, in which pieces ofdata are aligned in ascending or descending order, is read out to becompared with comparison target data in the first search. When thepieces of data are aligned in ascending order and if the comparisontarget data is smaller than the read out data, it means that thecomparison target data might exist within the first half of the searchrange. Accordingly, in the second search, the search range is newly setto the first half and a piece of data lying at the one-half position inthe range, i.e. at the one-quarter position in the original searchrange, is read out to be compared with the comparison target data.Conversely, if the comparison target data is greater than the read outdata, it means that the comparison target data might exist within thesecond half of the search range. Accordingly, the new search range isset to the second half and a piece of data lying at the one-halfposition in the range, i.e. at the three-quarter position in theoriginal search range, is read out to be compared with the comparisontarget data in the second search. In this way, the search range isnarrowed by half repeatedly until the target data is reached.

In the base technology, in contrast, three comparison circuits areprovided for binary search, so that when the data at the one-halfposition in the search range is compared with comparison target data forthe first search, the comparison for the second search between thecomparison target data and each of the pieces of data at the one-quarterand three-quarter positions in the search range can be simultaneouslyperformed in parallel. Thus, the first and second searches can beperformed at the same time, thereby reducing the time required to loadthe data from the database. Also, by operating three comparison circuitsin parallel, the number of comparisons can be reduced by half, therebyreducing the search time.

In the example of FIG. 13, three comparison circuits are provided toperform two searches simultaneously. When n searches are to be performedsimultaneously, 2^(n)−1 comparison circuits may be generally provided.The control circuit 36Z inputs each piece of data at the 1/2^(n),2/2^(n), . . . , and (2^(n)−1)/2^(n) positions in the search range intothe 2^(n)−1 comparison circuits respectively, and operates thecomparison circuits simultaneously in parallel to allow them to comparethe respective pieces of data with comparison target data. The controlcircuit 36Z then acquires the comparison results from the comparisoncircuits and determines if the comparison target data is found. If anyof the comparison circuits output a signal indicating that there hasbeen a data match, the control circuit 36Z will determine that thecomparison target data has been found and will terminate the binarysearch. If there is no such signal output, the process will be shiftedto the next search. If the comparison target data exists within thedatabase, the data must lie within a range between points where thecomparison results of the 2^(n)−1 comparison circuits change. In thecase where 15 comparison circuits are provided, for example, if thepiece of data at the 5/16 position is smaller than comparison targetdata and if the piece of data at the 6/16 position is greater than thecomparison target data, the comparison target data should lie within therange between the 5/16 and 6/16 positions. Thus, the control circuit 36Zacquires comparison results from the comparison circuits and sets thenext search range to a range between points where the comparison resultschange. The control circuit 36Z then inputs, into the respectivecomparison circuits, each piece of data at the 1/2^(n), 2/2^(n), . . . ,and (2^(n)−1)/2^(n) positions in the next search range thus set.

There are provided the three first databases 50 in the base technology:the first database 50A is connected to the comparison circuit 36A andsupplies thereto a piece of data at the one-quarter position in thesearch range; the first database 50B is connected to the comparisoncircuit 36B and supplies thereto a piece of data at the two-quarterposition in the search range; and the first database 50C is connected tothe comparison circuit 36C and supplies thereto a piece of data at thethree-quarter position in the search range. Therefore, pieces of datacan be loaded simultaneously into the comparison circuits in parallel,thereby further reducing the time for data loading and enablinghigh-speed binary search.

Providing more comparison circuits will improve the search speed. Inconsideration of cost or size of the system, a sufficient number ofcomparison circuits may be provided to achieve a desired search speed.Also, although it is desirable that first databases as many ascomparison circuits are provided, some comparison circuits may share adatabase in consideration of cost or size of the system.

FIG. 14 shows still yet another example of internal data of the firstdatabase. The first database 50 shown in FIG. 14 stores URLs of contentsto which filtering is applied. The data stored in the first database 50may include predetermined data recognized as a wild card, such as “00H”or “01H”. In the example shown in FIG. 14, “*********” is recognized asa wild card in “http://www.xx.xx/*********”, and, whatever thecomparison target data corresponding thereto is, it is determined in thecomparators 36 a, 36 b, etc. that such data matches the wild card.Accordingly, every character string starting with “http://www.xx.xx/” isdetected by the binary search circuit 36. Consequently, processing suchas applying filtering to all contents within the domain“http://www.xx.xx/” can be easily performed.

FIG. 15 shows an example of internal data of the second database. Thesecond database 60 includes a search result field 62, which contains asearch result of the search circuit 30, and a processing content field64, which contains a processing content to be performed on communicationdata. The database stores the search results and the processing contentsrelated to each other. In the example of FIG. 15, conditions areestablished such that a packet will be allowed to pass if itscommunication data contains reference data; if not, the packet will bediscarded. The process execution circuit 40 searches the second database60 for a processing content based on the search result and performs theprocessing on the communication data. The process execution circuit 40may also be configured with a wired logic circuit.

FIG. 16 shows another example of internal data of the second database.In the example of FIG. 16, the processing content is set for each pieceof reference data. With regard to packet replacement, replacement datamay be stored in the second database 60. As for packet routing orswitching, information on the route may be stored in the second database60. The process execution circuit 40 performs processing, such asfiltering, routing, switching, or replacement, which is specified in thesecond database 60, in accordance with the search result of the searchcircuit 30. When the processing content is set for each piece ofreference data, as shown in FIG. 16, the first database 50 and thesecond database 60 may be merged with each other.

The first database and the second database are configured to berewritable from the outside. By replacing these databases, various typesof data processing and communication control can be achieved using thesame communication control apparatus 10. Also, multistage searchprocessing may be performed by providing two or more databases thatstore reference data to be searched. In such instance, more complicatedconditional branching may be performed by providing two or moredatabases that store search results and processing contents related toeach other. When multiple databases are thus provided to conductmultistage search, a plurality of the position detection circuits 32,the index circuits 34, the binary search circuits 36, etc. may also beprovided.

The data intended for the foregoing comparison may be compressed by thesame compression logic. If both the source data and the target data tobe compared are compressed by the same method, the comparison can beperformed in the same manner as usual, thus reducing the amount of datato be loaded for comparison. The smaller amount of data to be loaded canreduce the time required to read out the data from the memory, therebyreducing the overall processing time. Moreover, the number ofcomparators can be also reduced, which contributes to theminiaturization, weight saving, and cost reduction of the apparatus. Thedata intended for comparison may be stored in a compressed form, or maybe read out from the memory and compressed before comparison.

FIG. 17 shows another illustrative configuration of the communicationcontrol apparatus in the base technology. The communication controlapparatus 10 shown in this diagram has two communication control units12, each of which has the same configuration as the communicationcontrol apparatus 10 shown in FIG. 4. There is also provided a switchcontrol unit 14 for controlling the operation of the individualcommunication control units 12. Each of the communication control units12 has two input/output interfaces 16 and is connected to two networks,upstream and downstream, via the respective input/output interfaces 16.The communication control units 12 receive communication data fromeither one of the networks and output processed data to the other. Theswitch control unit 14 switches the inputs and outputs of theinput/output interfaces 16 provided for the individual communicationcontrol units 12, thereby switching the directions of the flow ofcommunication data in the communication control units 12. This allowscommunication control not only in one direction but also in bothdirections.

The switch control unit 14 may provide control such that: either one ofthe communication control units 12 processes inbound packets and theother processes outbound packets; both the units process inboundpackets; or both the units process outbound packets. Consequently, thedirections of communications to control can be changed depending on, forexample, the traffic status or intended purpose.

The switch control unit 14 may acquire the operating state of therespective communication control units 12 and may switch the directionof communication control according thereto. For example, when one of thecommunication control units 12 is in a standby state and the othercommunication control unit 12 is in operation, the unit on standby maybe activated as a substitute upon detection of the unit in operationstopping due to a failure or other reasons. This can improve the faulttolerance of the communication control apparatus 10. Also when one ofthe communication control units 12 needs maintenance such as a databaseupdate, the other communication control unit 12 may be operated as asubstitute. Thus, appropriate maintenance can be performed withouthalting the operation of the communication control apparatus 10.

The communication control apparatus 10 may be provided with three ormore communication control units 12. The switch control unit 14 may, forexample, acquire the traffic status to control the direction ofcommunications in the respective communication control units 12 so thatmore communication control units 12 are allocated for communicationcontrol processing in a direction handling higher traffic. Thisminimizes a drop in the communication speed, even when the trafficincreases in one direction.

FIG. 18 shows a configuration of a communication control apparatus 10comprising multiple communication control apparatuses 10 a, 10 b, 10 c,etc. Since the first database 50 requires larger capacity in proportionto an increasing number of pieces of data, the database is divided intoportions to be stored by the communication control apparatuses 10 a, 10b, 10 c, etc. As will be discussed later, in the communication controlsystem 100 of the base technology, a communication packet to beprocessed is sent to all the communication control apparatuses 10 a, 10b, 10 c, etc. in operation, and each of the communication controlapparatuses 10 then receives and processes the packet. For example, thecommunication control apparatus 10 a stores data with data IDs“000001“-”100000”, the communication control apparatus 10 b stores datawith data IDs “100001“-”200000”, and the communication control apparatus10 c stores data with data IDs “200001“-”300000”; each of thecommunication control apparatuses refers to the respective data toprocess a packet.

FIG. 19 shows an example of internal data of a management table 111provided in the operation monitoring server 110. The management table111 includes apparatus ID fields 112, operating state fields 113 anddata ID fields 114. The apparatus ID fields 112 contain the apparatusIDs of the communication control apparatuses 10 a, 10 b, etc. Theoperating state fields 113 contain the operating state of thecommunication control apparatuses, and the data ID fields 114 containthe ranges of data IDs handled by the communication control apparatuses.The operating state appears as “operating”, “standby”, “failure”, “dataupdating”, etc. The operating state fields 113 are updated by theoperation monitoring server 110 each time the operating state of thecommunication control apparatuses 10 a, 10 b, etc. changes. In theexample shown in FIG. 19, “465183” pieces of data are stored in thefirst database 50, so that the five communication control apparatuses 10having the apparatus IDs “1“-”5” are in operation while thecommunication control apparatus 10 having the apparatus ID “6” is in astandby state.

The operation monitoring server 110 monitors the operating state ofmultiple communication control apparatuses 10. When detecting any of thecommunication control apparatuses 10 being inoperable because of sometrouble, the operation monitoring server 110 stores, in thecommunication control apparatus 10 on standby, the same data as storedin the inoperable apparatus, and places the standby communicationcontrol apparatus 10 in operation. For example, when the communicationcontrol apparatus 10 with the apparatus ID “2” halts the operationbecause of a failure, as shown in FIG. 20, the communication controlapparatus 10 with the apparatus ID “6”, which has been on standby,stores the data with data IDs “100001-200000” and starts operating.Thus, even if a communication control apparatus 10 stops because of sometrouble, the main operation will be continued properly. Thecommunication control apparatus 10 on standby may store any of the datain advance to be made in a hot standby state, or may be in a coldstandby state.

Next, the procedure for updating databases stored in the communicationcontrol apparatuses 10 will be described. The database server 150acquires the latest database from an external database at a certain timeand retains it therein. In order to reflect, in a communication controlapparatus 10, the latest database retained in the database server 150,the operation monitoring server 110 transfers the data from the databaseserver 150 and stores it in the communication control apparatus 10 at acertain time.

FIGS. 21A, 21B and 21C are diagrams for describing the procedure forupdating databases. As with FIG. 19, FIG. 21A shows that thecommunication control apparatuses 10 with the apparatus IDs “1“-”5” arein operation while the communication control apparatus 10 with theapparatus ID “6” is on standby. At the time when a database is to beupdated, the operation monitoring server 110 identifies thecommunication control apparatus 10 in a standby state then and instructsthe database server 150 to store the data in the communication controlapparatus 10. In the example shown in FIG. 21A, the communicationcontrol apparatus 10 with the apparatus ID “6” is on standby, so thatthe database server 150 stores the data in that apparatus. The operationmonitoring server 110 then changes the operating state field 113 for theapparatus ID “6” to “data updating”.

FIG. 21B shows a state where a database of a communication controlapparatus 10 is being updated. The database server 150 stores, in thefirst database 50 in the communication control apparatus 10 with theapparatus ID “6” on standby, the data handled by one of thecommunication control apparatuses 10 in operation. In the example shownin FIG. 21B, the data with data IDs “000001-100000”, which have beenhandled by the communication control apparatus 10 with the apparatus ID“1”, are stored in the communication control apparatus 10 with theapparatus ID “6”.

FIG. 21C shows a state where the communication control apparatus 10 withthe apparatus ID “6” has had its database updated and is placed inoperation, and the communication control apparatus 10 with the apparatusID “1” is placed into a standby state instead. Upon completion ofstoring data in the communication control apparatus 10 with theapparatus ID “6”, the operation monitoring server 110 starts theoperation of the apparatus, which stores the updated database. Theoperation monitoring server 110 also stops the operation of thecommunication control apparatus 10 with the apparatus ID “1”, whichstores the database before update, to place the apparatus into a standbystate. Thus, the communication control apparatus 10 with an updateddatabase is placed in operation. Then, the data with data IDs“100001-200000” are stored in the communication control apparatus 10with the apparatus ID “1” before the apparatus is placed in operation,and, subsequently, the operation of the communication control apparatus10 with the apparatus ID “2” is stopped. Thereafter, databases aresimilarly updated by turns, so that the databases of all thecommunication control apparatuses 10 can be updated behind the actualoperation, without halting the operation of the communication controlsystem 100.

In this way, data stored in each of the communication controlapparatuses 10 is not fixed in the base technology, and hence, thecommunication control apparatus 10 that stores certain data changes withtime. If, before a packet is sent to each of the communication controlapparatuses 10, the process of determining which communication controlapparatus 10 stores the data of the user is performed, the time for theprocess will be additionally required. Accordingly, in the presentembodiment, a received packet is provided to all the communicationcontrol apparatuses 10, and each of the apparatuses then processes thepacket. In the following, a technique for providing such mechanism willbe described.

FIG. 22 shows a configuration of a communication path control apparatusprovided to process packets with multiple communication controlapparatuses 10. A communication path control apparatus 200 comprises aswitch 210, an optical splitter 220, which is an example of a datasupply unit, and a switch 230. The switch 210 transmits a receivedpacket to the communication control apparatuses 10. Between the switch210 and the communication control apparatuses 10, there is provided theoptical splitter 220 that provides the packet to the multiplecommunication control apparatuses 10 a, 10 b and 10 c in parallel. Theswitch 210 practically transmits a packet to the optical splitter 220,which transmits the packet to each of the communication controlapparatuses in parallel.

If a packet is converted to a broadcast packet so as to be transmittedto the multiple communication control apparatuses 10 a, 10 b and 10 c,additional process such as adding a time stamp to the header will berequired, which reduces the processing speed. Therefore, a packet is notconverted but split by the optical splitter 220 so as to be transmittedas a unicast packet to the multiple communication control apparatuses 10a, 10 b and 10 c. This method will be called “parallelcast” in thepresent specification.

Each of the communication control apparatuses is not set to a mode inwhich an apparatus receives only packets directed to the MAC address ofthe apparatus, but set to promiscuous mode in which an apparatusreceives all packets regardless of the destination MAC addresses. Whenreceiving a packet sent via parallelcast from the optical splitter 220,each of the communication control apparatuses omits MAC address matchingand acquires every packet to process it.

If a packet needs to be returned to the transmission source because, forexample, the communication thereof has been prohibited, thecommunication control apparatus 10 c will transmit a response packet tothe switch 210 bypassing the optical splitter 220. If the communicationcontrol apparatus 10 c processes the packet and the communicationthereof is permitted, the communication control apparatus 10 c willtransmit the packet to a network. Between the communication controlapparatuses 10 and the upstream communication line, there is providedthe switch 230 by which packets transmitted from the multiplecommunication control apparatuses 10 a, 10 b and 10 c are aggregated.The communication control apparatus 10 c will practically transmit thepacket to the switch 230, which transmits the packet to the upstreamcommunication line.

When the switch 230 receives a return packet transmitted from thedestination of packet transmission and if the return packet need not beprocessed by the communication control apparatuses 10, the packet willbe transmitted from the port 232 of the switch 230 to the port 212 ofthe switch 210, and then transmitted therefrom to the transmissionsource. On the Internet, the transmission path is generally recorded inthe packet to ensure the return path through which a response packetsent in return for the packet can be certainly delivered to thetransmission source. In the present embodiment, however, since thereturn path is already provided within the communication path controlapparatus 200, communication can be performed between apparatuseswithout recording the path or processing the packet. Consequently,unnecessary process can be eliminated, thereby improving the processingspeed.

The example in FIG. 22 shows the case where only a packet transmittedfrom a transmission source to a transmission destination is processed,but a return packet transmitted from the transmission destination to thetransmission source is made to pass through without being processed.Alternatively, the communication path control apparatus 200 may beconfigured so that the communication control apparatuses 10 processpackets transmitted in both directions. In such case, the opticalsplitters 220 may be provided on both sides of the communication controlapparatuses 10. Also, the bypass path from the switch 230 to switch 210need not be provided.

In such way, by sending a packet via parallelcast to all thecommunication control apparatuses, the packet can be appropriatelyprocessed by the proper communication control apparatus among themultiple communication control apparatuses, without the need to specify,in advance, a communication control apparatus by which the packet is tobe processed.

Since these communication control apparatuses receive all packets sentvia parallelcast from the communication path control apparatus 200 toprocess or discard them, as stated previously, the apparatuses need notbe provided with IP addresses, which uniquely identify apparatuses onthe Internet. If the packet processing as discussed above is performedby server apparatuses or the likes, it will be necessary to considerattacks to the server apparatuses. However, since the communicationcontrol apparatuses of the present embodiment cannot be directlyattacked by malicious third parties via the Internet, communicationcontrol can be performed securely.

Embodiment

FIG. 23 shows a configuration of a communication management systemaccording to the embodiment. A communication management system 300 usesthe communication control apparatus 10 having a packet filteringfunction, etc. to perform processing for detecting and blockinginappropriate communication, such as communication for operating a bot.

As discussed previously, a bot infects and damages a user terminal 310.A user terminal infected by a bot (hereinafter, referred to as “bot320”) is operated at the attacker's discretion and behaves as theattacker's own terminal. Therefore, it is desired to detect and blockcommunication for operating a bot 320 or communication through which abot 320 attacks another user terminal 310.

However, since new subspecies appear constantly based on a bot of whichthe source code has become available, it is difficult to certainlydetect every inappropriate communication data transmitted from or to abot 320 or a botnet 322, which consists of multiple bots 320.

For such an occasion, the present embodiment proposes a technique, withthe perspective reversed, in which a signature list of normalcommunication is created so as to permit normal communication; at thesame time, every abnormal communication is reported to be analyzed, andboth the signature list of normal communication and the signature listof abnormal communication are updated as needed. This technique isexpected to reduce damage caused by botnets, so that the socialcontribution of the present invention may be considered remarkable.

In the communication management system 300, the communication controlapparatus 10 is provided between a user terminal 310 and the Internet390 to control communication data transmitted via the Internet 390. Whendetecting abnormal communication data, the communication controlapparatus 10 notifies an operator terminal 340 thereof. The operatorterminal 340 then analyzes such communication data to determine if thecommunication data is normal. The signature of communication data foundto be normal is reflected in the communication control apparatus 10 and,thereafter, the transmission of the same kind of communication data willbe permitted. The signature of communication data found to be abnormalis also reflected in the communication control apparatus 10 and,thereafter, the transmission of the same kind of communication data willbe forbidden and blocked. In this way, the communication controlapparatus 10 detects and blocks communication between a bot 320 and abotnet 322 or communication for operating a bot 320 via the Internet390.

The communication control apparatus 10 of the present embodimentcomprises, as the first database 50, a normal signature list 332, anabnormal signature list 334 and a rule database 336. The normalsignature list 332 contains a list of signatures of communication dataof which the transmission is considered to be normal and should bepermitted. The abnormal signature list 334 contains a list of signaturesof communication data of which the transmission is considered to beabnormal and should be blocked. The rule database 336 stores a rule forextracting communication data required to be analyzed.

Since the three first databases 50 are provided, there are also providedthree search circuits 30: a search circuit 30A functions as a firstsearch unit, which searches the normal signature list 332 storingsignatures of normal communication to check if the signature of acquiredcommunication data appears in the list; a search circuit 30B functionsas a second search unit, which searches the abnormal signature list 334storing signatures of abnormal communication to check if the signatureof acquired communication data appears in the list; and a search circuit30C functions as a third search unit, which searches the rule database336 to check if acquired communication data complies with a rule storedin the database. At least two, or preferably all, of these searchcircuits 30 perform searches simultaneously in parallel. This enablesfast detection of normal communication, abnormal communication, andcommunication to be extracted, without reducing throughput. In order toprovide communication data to the three search circuits 30 concurrently,the technique shown in FIG. 22 may be used.

The second database 60 stores a processing content of issuing a warningfor the case where there is detected communication data of which thesignature does not match any signature of normal communication stored inthe normal signature list 332. In such case, the process executioncircuit 40 functions as a warning unit that, when the search circuit 30Adetects communication data of which the signature does not match anysignature stored in the normal signature list 332, issues a warning tonotify the operator terminal 340 thereof.

The second database 60 also stores a processing content of blockingcommunication data for the case where there is detected communicationdata of which the signature matches a signature of communication to beblocked stored in the abnormal signature list 334. In such case, theprocess execution circuit 40 functions as a blocking unit that, when thesearch circuit 30B detects communication data of which the signaturematches a signature stored in the abnormal signature list 334, discardsand blocks the communication data.

In the operator terminal 340, when acquiring a warning from thecommunication control apparatus 10, a warning acquisition unit 342notifies the operator thereof through a display output or an audiooutput. In the meantime, a communication data acquisition unit 344acquires from the communication control apparatus 10 the communicationdata against which the warning has been issued. An analysis unit 346analyzes communication data against which a warning has been issued andof which the signature does not match any signature of normalcommunication so as to determine if the communication is normal, andthen transmits the result to a determination result acquisition unit348. The determination result acquisition unit 348 may acquire thedetermination result from the operator who has analyzed thecommunication data. Alternatively, the determination result acquisitionunit 348 may acquire the determination result from a security vendor orthe like specified by the operator.

When acquiring a determination result that communication data againstwhich a warning has been issued is found to be normal, the determinationresult acquisition unit 348 instructs a normal signature list updateunit 352 to add the signature of the communication data to a normalsignature list 362. The normal signature list update unit 352 then addsto the normal signature list 362 the signature of the communication datafound to be normal.

When acquiring a determination result that communication data againstwhich a warning has been issued should be blocked, the determinationresult acquisition unit 348 instructs an abnormal signature list updateunit 354 to add the signature of the communication data to an abnormalsignature list 364. The abnormal signature list update unit 354 thenadds to the abnormal signature list 364 the signature of thecommunication data to be blocked.

The normal signature list 362 and abnormal signature list 364 thusupdated are reflected, at a certain time, in the normal signature list332 and abnormal signature list 334 of the communication controlapparatus 10 by the database server 150. Updating of a database may beperformed according to the procedure described in the base technology.Alternatively, the normal signature list update unit 352 and abnormalsignature list update unit 354 may directly access and update the normalsignature list 332 and abnormal signature list 334. When multiplecommunication control apparatuses 10 are provided, the database server150 creates the normal signature list 362 that collectively containsdetermination results of communication data against which warnings havebeen issued by the respective communication control apparatuses 10, soas to reflect the collective normal signature list 362 in the normalsignature lists 332 of the respective communication control apparatuses10.

In this way, instead of only extracting the signature of abnormalcommunication to block the communication, the signature of normalcommunication alone is extracted to permit the communication; the othercommunication is analyzed and determined if it is normal, and thedetermination result is reflected thereafter. Accordingly, even thoughinappropriate communication is conducted using a new communicationprotocol in the botnet 322 or the like, the communication is notconsidered to be normal and can be detected certainly. Also, oncecommunication data to be blocked is detected, the signature thereof isregistered in the abnormal signature list 334 so that the communicationdata can be appropriately blocked thereafter. Although the number ofsignatures included in the normal signature list 332 and abnormalsignature list 334 becomes considerably large, communication can bemanaged appropriately without reducing throughput, because thecommunication control apparatus 10 of the present embodiment isconfigured with dedicated hardware, and hence, high-speed searchprocessing can be achieved, as described in the base technology.

The second database 60 further stores a processing content ofreplicating communication data and outputting it for the case wherethere is detected communication data that complies with a rule stored inthe rule database 336. In such case, the process execution circuit 40functions as an extraction unit that, when the search circuit 30Cdetects communication data that complies with a rule stored in the ruledatabase 336, outputs a replica of the communication data from an outputport to the operator terminal 340.

For example, when determining whether communication data against which awarning has been issued is normal or to be blocked, it may be necessary,for the analysis, to refer to other communication data transmitted fromthe same source or other communication data transmitted to the samedestination. For such an occasion, if the IP address of the transmissionsource or transmission destination of the communication data againstwhich a warning has been issued, or the content of the payload of suchcommunication data is registered as one of the rules in the ruledatabase 336, communication data that complies with the rule can becollected and used for the analysis. As described in the basetechnology, since the communication control apparatus 10 of the presentembodiment can detect not only information stored in a header field,such as the IP address of a transmission source or a transmissiondestination, but also information stored in a payload field, the rulescan be set in more detail.

If the operator decides that communication data against which a warninghas been issued should be analyzed with reference to other communicationdata, the operator may add a rule for extracting relevant communicationdata to a rule database 366 via a rule database update unit 356. Theupdated rule database 366 is reflected in the rule database 336 of thecommunication control apparatus 10 by the database server 150. Thisenables a packet capture apparatus that can modify a signature asneeded.

The present invention has been described with reference to theembodiment. The embodiment is intended to be illustrative only and itwill be obvious to those skilled in the art that various modificationsto constituting elements or processes could be developed and that suchmodifications are also within the scope of the present invention.

Although the normal signature list 332, abnormal signature list 334,rule database 336, and the search circuits 30A, 30B and 30C, whichsearch such lists and database for communication data, are provided in asingle communication control apparatus 10 in the present embodiment,these may be provided in different communication control apparatuses 10.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a communication management systemthat manages inappropriate communication.

1. A communication management system, comprising: a normal signaturelist which stores a list of signatures of normal communication; a firstsearch unit which acquires communication data and searches the normalsignature list storing signatures of normal communication to check ifthe signature of the communication data appears in the list; and awarning unit which issues a warning when there is detected communicationdata of which the signature does not match any signature of normalcommunication stored in the normal signature list.
 2. The communicationmanagement system of claim 1, further comprising: a determination resultacquisition unit which acquires a determination result indicatingwhether or not communication data against which a warning has beenissued is normal; and a normal signature list update unit which, whenthe determination result acquisition unit acquires a determinationresult that communication data against which a warning has been issuedis found to be normal, adds the signature of the communication data tothe normal signature list.
 3. The communication management system ofclaim 1, further comprising: an abnormal signature list which stores alist of signatures of communication to be blocked; a second search unitwhich acquires communication data and searches the abnormal signaturelist storing signatures of communication to be blocked to check if thesignature of the communication data appears in the list; and a blockingunit which, when there is detected communication data of which thesignature matches a signature of communication to be blocked stored inthe abnormal signature list, blocks the communication data.
 4. Thecommunication management system of claim 3, wherein the determinationresult acquisition unit further acquires a determination resultindicating whether or not communication data against which a warning hasbeen issued should be blocked, the communication management systemfurther comprising an abnormal signature list update unit which, whenthe determination result acquisition unit acquires a determinationresult that communication data against which a warning has been issuedshould be blocked, adds the signature of the communication data to theabnormal signature list.
 5. The communication management system of claim1, further comprising: a rule database which stores a rule forextracting communication data required to be analyzed among acquiredcommunication data; a third search unit which acquires communicationdata and searches the rule database to check if the communication datacomplies with a rule stored in the database; and an extraction unitwhich, when there is detected communication data complying with a rulestored in the rule database, extracts the communication data.
 6. Thecommunication management system of claim 5, further comprising a ruledatabase update unit which adds, to the rule database, a rule forextracting communication data associated with communication data againstwhich a warning has been issued.
 7. The communication management systemof claim 1, wherein at least one of the first search unit, the secondsearch unit and the third search unit is configured with a wired logiccircuit.
 8. The communication management system of claim 7, wherein atleast two of the first search unit, the second search unit and the thirdsearch unit perform searches simultaneously in parallel.
 9. Acommunication management method, comprising: searching, upon acquisitionof communication data, a normal signature list storing a list ofsignatures of normal communication so as to check if the signature ofthe communication data appears in the list; and issuing a warning whenthere is detected communication data of which the signature does notmatch any signature of normal communication stored in the normalsignature list.